The Late Effects of Normal Tissue (LENT) conferences are a succession of meetings held over the past two decades with the ultimate goal of developing a systematic and reproducibly effective scoring systems and approaches to the management of the chronic adverse consequences of cancer therapy. The LENT conferences have had, and continue to have, international cooperation and major impact on protocol design in the Radiation Therapy Oncology Group (RTOG) and the European Organization for Research and Treatment of Cancer (EORTC). The importance of accurately assessing chronic toxicity is even more obvious with the introduction of new therapeutic techniques with delivery of very high, intensely concentrated doses in very short times (e.g. conformal radiation therapy, radiosurgery, radionuclide therapy, high-dose rate brachytherapy, intensity-modulated radiation therapy), and the aggressive integration of chemotherapy, radiation therapy, and biologic response modifiers. The era of molecular biology, which is permitting the exploration of cytokine and gene therapy, further stresses the critical need to accurately determine therapeutic ratios. Thus there is a pressing need to refine protocols which will complete validation of the LENT scales. With respect to the pediatric and young adult (20 years) population, chronic normal tissue damage is clearly a critical consequence of successful cancer therapy. Such late effects impact on the quality of life, and in part determine the aggressiveness of therapy. Pediatric late effects assume increased importance due to the potential life span of survivors, and the sensitivity of developing normal tissues to cytotoxic therapy. The goals of LENT Consensus Conference IV will be multiple and focus on (i) validating the effectiveness of scales defined in previous LENT conferences, (ii) extending LENT Scales to include molecular biomarkers of normal tissue damage, and (iii) modifying LENT scales for application to the PEDIATRIC population. In addition, it is now possible to discuss the (iv) development of predictive assays and interventions for normal tissue damage with precise assessments of their efficacy. These are achieved with the aid of the accurate grading of therapy-induced toxicities that grew out of the previous LENT conferences and the subsequently completed clinical and laboratory studies with (v) proper statistical analysis. The proposed date of the conference is 10/29/2001 to 11/1/2001.